Dynamic date format in text output step in PDI - pentaho-data-integration

Question

I am using PDI to run sql queries stored in an oracle DB and then extracting the results to a file using a text file output step. Every extract is different so I can't set the output fields. How can I default the date format of the output to whatever is specified for that particular extract?
I have a lookup table with the SQL query and the date format I want for that query.
I realise I could use formatting on the query itself, but I would like to know if it can be done in PDI instead. There are literally hundreds of these so it would mean far less work.

Answer 1

There is no-standard way, I know to do this. Except of course to use a User Defined Java Class or a Metadata Injector.
However, the data format is irrelevant in PDI up to when you want to write them on a file. And even if you have hundreds of possible on the input (which does not bother Kettle at all), I am sure you have relatively few of them on the output.
So, just before the last output step, have a lookup in your table, and switch to the approriate Select value step, in which the Metadata tag allows you to attach a format to a Date field, before to drop the flow in your Text output step with unspecified field.

Answer 2

Well, I don't know this would help or not but here is what I do to extract the date and use it in Text File Output step or even in Table Input/Output or Execute SQL step.
Do it in Job Level, split it into several transformation and use Set variable or Copy row to result step.
1st Transformation called DateTime transformation. In this transformation where you create dynamic datetime value that we will use later.
Use Get System Info step, make a field [Fieldname] with Type is : system date (variable). [Fieldname] will contain current datetime when that transformation run.
Add Calculator Step, in here you do split the datetime [Fieldname] from Get System Info into several part.
Example (focus on this column)
Usually I split it into Day, Month, Year, Hour, Minute
New Field | Calculation | Field A | Value type
-----------+-------------------------------+-------------+-----------
Daytrans | Day of month of Date A | [Fieldname] | String
Monthtrans | Month of Date A | [Fieldname] | String
Yeartrans | Year of Date A | [Fieldname] | String
Hour | Hour of Day of Date A | [Fieldname] | String
Minute | Minute of Hour of Date A | [Fieldname] | String
Filename | Set Field to Constant Value A | "Filename_" | String
Note. "Filename_" with no quotation.
Use Formula step to combine that date into whatever format you want.
Example. (yyyymmdd, yyyy/mm/dd)
New Field | Formula | Value type
------------------------------------------------------------------------------------------
yyyymmdd | [Filename] & [Yeartrans] & [Monthtrans] & [Daytrans] | String
yyyy/mm/dd | [Filename] & [Yeartrans] & "/" & [Monthtrans] & "/" & [Daytrans] | String
Note. You can creatively make your datetime format depend on your need.
and make condition like this in Formula step:
[Yeartrans] & if([Monthtrans] < 10; "0" & [Monthtrans]; [Monthtrans]) & if([Daytrans] < 10; "0" & [Daytrans]; [Daytrans]).
I usually use it when i want the result is like this 20190701.
Why? Because if not using if function the result will like this 201971, without 0 on July 1st, 2019.
Use Select Value step to filter the field that you want to use, only this [yyyymmdd] and this [yyy/mm/dd] field.
Last is use Set variable or Copy row to result step, so you can use it in another transformation.
2nd Transformation called Data Processing
Use Get Row from result or Get Variable step and fill it with [fieldname] or variable that we made before.
Here is your data, whatever is it, from table, execute query, anything.
Text File Output step, where the configuration is in Filename box, you only need call the variable using this : ${Variablename}
Done. And don't forget in Text File Output,Fields tab, fill it automatically using button Get Field or manually by your self.
You can also use that datetime variable in query, just check the variable subtitution box in Execute Query step or Replace variable in script box in Table Input step. Or output it as data in file by join 2 source using Join Row (Cartesian).
The Result will like this : Filename_20190701.csv
Sorry for my bad English, but hopefully this help.